Xanthoriicola physciae
≡*Gymnosporium physciae Kalchbr., Hedwigia 4: 120 (1865).
Description : Lichenicolous, on apothecia of Xanthoria parietina, the apothecia (and thallus) becoming discoloured, turning sooty black and eventually dying. Conidiophores immersed in hymenium of host, not forming sporodochia. Conidiogenous cells phialidic, terminal, subcylindrical, ampulliform, brownish, 6–11 × 3.5– 5.5 μm. Conidia solitary, spherical, simple, brown, verruculose, not adhering in chains, 3.5–6 μm diam.
N: Northland (Russell). S: Canterbury (Riccarton Bush Christchurch), Otago (Moeraki Point) (Dr S.Y. Kondratyuk, pers. comm.). On coastal rocks, and on Quercus robur in a suburban park. Widespread in Europe, Great Britain, Scandinavia and the Canary Is (Hawksworth & Punithalingam 1973; Hawksworth 1979a; Diederich 1989; Santesson 1993; Hafellner 1995c; Triebel & Scholz 2001; Kukwa 2002c; Martínez et al. 2002; Preece & Blackwell 2004). Apparently not present in North America (Essslinger & Egan 1995). Known also from Australia (Dr Sergey Kondratyuk, pers. comm.).
?Cosmopolitan
Host : Xanthoria ligulata, X. parietina, ? X. polycarpa.
Illustrations : Hawksworth & Punithalingam (1973: 68, fig. 7); Hawksworth (1979a: 267, fig. 42A–G); Boqueras (2000: 459, fig. 79 I); Preece & Blackwell (2004: 8, fig. 1).
* Xanthoriicola physciae is characterised by: the lichenicolous habit; the sooty, black discolouration of the host tissue; and the simple, brown, spherical conidia, 3.5–6 μm diam., with a verruculose wall.
